Grounding House Bank

Lin · August 26, 2010, 04:52:33 PM

I am about to install the Vanner 60-50 I have as my OTR battery charger for the house bank. As many know, this can work perfectly fine as an alternative to having an separate 12 volt alternator. Simply connect the 24 volt post to 24v at the start batteries, the 12v post to the house bank positive, and the negative post to a good negative or chassis ground. Without a common negative, it won't work. So, while scoping out the job, I noticed that I really do not have a serious ground-to-chassis cable from the house bank. This bank is also used to start the generator, so it is grounded through a #4 wire going to that generator. I have not noticed any problems with this setup to date and wondered if it is adequate or whether I should have a more substantial ground cable directly from the batteries to the chassis.

FloridaCliff · August 26, 2010, 05:12:10 PM

Lin,

I have a similar setup to you.

Except my ground from the batteries goes to a large feed thru stud (Bulkhead between batteries and first bay) and my batteries ground attaches to it. Another ground attaches to the same lug and feeds to the engine.etc And a 3rd cable runs to the generator ground My Vanner attaches to the same lug on the other side of the bulkhead.

The ground stud on my GMC is factory standard.

I would ground it to a bulkhead, somewhere, preferably near the batteries.

.

Cliff

Lin · August 26, 2010, 07:12:20 PM

Cliff,

I like the idea of setting up a lug on the bulkhead. Looks like that's the way I will go.

gumpy · August 27, 2010, 06:37:18 AM

Well, I can tell you this. Two years ago I moved my batteries and electrical to make room for my generator. I forgot to reinstall the frame ground for the batteries. It caught up to me
this summer when I tried to use the house A/C while charging off the bus alternator. The only ground wire the charging system could find was a little 12ga wire that went to my Aquahot.
Lets just say I figured out the mistake after we cleared all the smoke out of the bus. We then put everything back in the bays and made a temporary fix, and when I got back home, I
remedied the problem by drilling a hole through the steel edge of the bay partition and bolting a cable between the battery negative bus frame.

The house batteries and inverter should be grounded to the frame at the same stud, ideally. The generator is probably internally bonded and so the frame bonds it to the bus frame if it's bolted in place. But you should check this with a meter, and install a frame bond if necessary. The coach batteries will already be bonded to the frame somewhere in the bus. Ideally, they should all be bonded to the bus frame at the same point, but this is not usually practical. I would use nothing smaller than 2/0 cable.

BG6 · August 27, 2010, 08:18:21 AM

In my 96A3, the coach batteries are just behind the RF wheel well. Since I mounted the house batteries in the last bay, I didn't want to run to the grounding lug in the battery bay.

I (CAREFULLY!!!) drilled a 1/2" hole through the tunnel wall, scraped the paint off a circle around the hole, then ran a bolt through the hole, put a fender washer on it, then a lockwasher and nut, cranked way down. This left me about an inch and a half of the bolt to serve as my grounding lug, with plenty of room for the thick lugs on the 4/0 cables from the two house battery banks, as well as the Vanner, inverter, etc.

BTW, I put the Vanner grounding lug at the top of the stack -- that way I can shut off the Vanner without having to disconnect anything else.

Lin · August 27, 2010, 11:52:00 AM

I am now about halfway through the project. I have drilled and cleaned the bulkhead, installed a bolt as a lug, and have grounded the batteries to it with a #2 cable. I have changed the proposed location of the equalizer, so that will have to have its own ground to the chassis. I have also connected a dash switch to a relay to turn the equalizer (which is really just being used as a charger) on when I want it.

My question now is about connecting the 12v Vanner lug to the 12v bank. I could run it directly to the batteries which would give me about a 7+foot run. I could save several feet by connecting it to the positive lug on the inverter. I do not see what problems this could create since the two devices will be connected anyway through the batteries, but wanted to know if any of you know something that I am missing. Thanks

gumpy · August 27, 2010, 02:34:38 PM

Quote from: Lin on August 27, 2010, 11:52:00 AM

My question now is about connecting the 12v Vanner lug to the 12v bank. I could run it directly to the batteries which would give me about a 7+foot run. I could save several feet by connecting it to the positive lug on the inverter. I do not see what problems this could create since the two devices will be connected anyway through the batteries, but wanted to know if any of you know something that I am missing. Thanks

If your inverter positive is connected directly to the batteries, then it should be ok to connect the vanner wire to the inverter stud.

Note, you should have disconnects between your house bank and your inverter, as well as a fuse, located close to the battery.
You should also have a disconnect and fuse on the output from the vanner.

Lin · August 27, 2010, 04:58:12 PM

Craig,

Thanks for the reminder. I have fuses for both input and output for the equalizer, but overlooked getting one for the inverter. I just looked online and see some breakers cost more than I paid for the inverter. Are the cheap ones they sell for audio systems adequate? Do you know a good source disconnect/breakers?

Jriddle · August 27, 2010, 05:38:33 PM

My 100 amp Vanner has a fusible link on the out put wire. I didn't install another fuse because of this. Should I?

John

Lin · August 27, 2010, 08:48:27 PM

The Vanner Owner's Manual is down-loadable. The one I have says the 100 amp equalizer takes an 80 amp fuse on the 24v side and a 125 amp fuse on the 12v side. I used one of the types used for car audio which can be very reasonable. If yours has a fuse on the output, maybe it is not original. Anyway, if it is for 125 amps, it would seem to cover that side.

BG6 · August 28, 2010, 10:15:19 AM

Quote from: Lin on August 27, 2010, 11:52:00 AM
My question now is about connecting the 12v Vanner lug to the 12v bank. I could run it directly to the batteries which would give me about a 7+foot run. I could save several feet by connecting it to the positive lug on the inverter. I do not see what problems this could create since the two devices will be connected anyway through the batteries, but wanted to know if any of you know something that I am missing. Thanks

I think I'd go straight to the batteries. For the extra couple of bux worth of wire, you would not be trying to run the extra amps through the inverter lead, and simplifying the future job of removing or rewiring either one.

My Vanner is hooked up with 4 AWG welding wire. You want as many tiny strands as possible -- DC flows on the SURFACE of each strand.

Lin · August 28, 2010, 01:05:04 PM

BG,

Although I can be exceedingly cheap, in this case I was just looking to keep the run shorter which I consider preferable. It turned out though that my estimate was wrong (surprise, surprise!) and direct to the battery was about equal.